Five-Field Cron vs Quartz Cron
Separate Unix cron, Quartz cron, seconds fields, year fields, and ? placeholders before moving expressions between schedulers.
Read the five fields before previewing
For */15 9-17 * * MON-FRI, processing expands minutes 0,15,30,45, hours 9 through 17, and weekdays Monday through Friday. The preview starts after the selected minute, supports browser local time or UTC, returns at most 12 rows, and searches at most 366 days.
Reject shifted Quartz input
0 */5 9-17 * * MON-FRI has six fields and is rejected here rather than treating 0 as minute and */5 as hour. Quartz may also define ?, L, W, #, and a year field; none of those meanings should be guessed by a Unix parser.
Verify semantics with expected timestamps
Use a fixed timezone and start value as evidence. In UTC, 0 9 15 * MON starting at 2026-07-13 08:59 yields 2026-07-13 09:00 and 2026-07-15 09:00 because the implemented Unix day-of-month/weekday rule is OR. Compare these timestamps and actual scheduler logs with the target platform documentation.
FAQ
About this topic
Why is 0 */5 * * * * rejected?
It is a six-field expression, usually with a seconds field. This tool parses five-field Unix cron only.
Can I use ? in Unix cron?
Usually no. ? is more common in Quartz-style expressions.
Does a five-field preview prove the job will run?
No. It proves only this parser's interpretation. Verify timezone, enabled state, permissions, environment, platform extensions, and actual scheduler logs.
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